This application claims priority from Korean Patent Application No. 2002-71396, filed on Nov. 16, 2002, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates to a lithium battery, and more particularly, to a lithium battery with an anode containing lithium metal.
2. Description of the Related Art
Lithium metal available as an anode active material for electrochemical batteries theoretically has a high energy density of about 3,860 mAh/g. However, a longer lifespan is not ensured to a secondary battery with a lithium anode. This is the reason why secondary batteries using a lithium anode are not commercially available yet.
In a lithium secondary battery using a lithium anode, the repeated charging-discharging cycles lead to the growth of dendrites on the lithium metal anode, which causes internal short-circuit of the battery, and the formation of mossy dead lithium crystals on the anode, which reduces the capacity of the lithium metal anode. Due to these problems, it is difficult for secondary batteries using a lithium anode to obtain a longer lifespan.
The formation of dendrites and/or dead lithium on a lithium anode during repeated charging-discharging cycles is known to be caused mainly by the interaction between the lithium metal and an electrolyte. In this regard, many attempts to solve these problems have been tried in a variety of aspects in the field.
U.S. Pat. Nos. 5,961,672; 6,017,651, and 6,025,094 disclose methods of forming a protective film on the surface of a lithium anode to prevent the lithium anode from contacting an electrolyte.
Matsuda et al. discloses a method for reducing the reactivity of a lithium anode with an electrolyte, in which metallic ions derived from, for example, Ga, Mg, In, etc., are added into the electrolyte so that a lithium alloy is formed on the surface of the lithium anode after interaction between the anode and the electrolyte [Y. Matsuda, J. Power Sources, 43, 1 (1993); Y. Matsuda et al., J. Power Sources, 68, 501 (1997); Y. Matsuda et al., J. Electroanal Chem, 473, 279(1999)].
Japanese Patent Laid-open Publication No. 2000-58120, U.S. Pat. Nos. 6,017,651 and 6,165,644 disclose methods of adding an inorganic metal salt producing positive ions of metals, such as Al, Mg, Sn, Ga, and In, that form an alloy with lithium, and negative ions, such as I−, Cl−, and ClO4−, into an electrolyte.